Search Results (12)

A novel piezoresistive cantilever microprobe (PCM) with an integrated electrothermal or piezoelectric actuator has been designed to replace current commercial PCMs, which require external actuators to perform contact-resonance imaging (CRI) of workpieces and avoid unwanted “forest of peaks” observed at large travel speed in the millimeter-per-second range. Initially, a PCM with integrated resistors for electrothermal actuation (ETA) was designed, built, and tested. Here, the ETA can be performed with a piezoresistive Wheatstone bridge, which converts mechanical strain into electrical signals by boron diffusion in order to simplify the production process. Moreover, a new substrate contact has been added in the new design for an AC voltage supply for the Wheatstone bridge to reduce parasitic signal influence via the EAM (Electromechanical Amplitude Modulation) in our homemade CRI system. Measurements on a bulk Al sample show the expected force dependence of the CR frequency. Meanwhile, fitting of the measured contact-resonance spectra was applied based on a Fano-type line shape to reveal the material-specific signature of a single harmonic resonator. However, noise is greatly increased with the bending mode and contact force increasing on viscoelastic samples. Then, to avoid unspecific peaks remaining in the spectra of soft samples, cantilevers with integrated piezoelectric actuators (PEAs) were designed. The numbers and positions of the actuators were optimized for specific CR vibration modes using analytical modeling of the cantilever bending based on the transfer-matrix method and Hertzian contact mechanics. To confirm the design of the PCM with a PEA, finite element analysis (FEA) of CR probing of a sample with a Young’s modulus of 10 GPa was performed. Close agreement was achieved by Fano-type line shape fitting of amplitude and phase of the first four vertical bending modes of the cantilever. As an important structure of the PCM with a PEA, the piezoresistive Wheatstone bridge had to have suitable doping parameters adapted to the boundary conditions of the manufacturing process of the newly designed PCM. Full article

This paper expands a recently proposed peak current-mode (PCM) control method for a power factor correction (PFC) boost converter to include the totem-pole converter and solves the controller’s compatibility problem with the totem-pole converter by proposing three input current sensing methods. Using MATLAB/Simulink 2023b, simulation experiments on a 2 kW totem-pole converter utilizing the PFC PCM controller were carried out to assess the performance of the controller with the proposed sensing methods. The findings indicate that under steady-state conditions, all three proposed sensing methods performed input current shaping successfully and yielded nearly identical THD% of about 4.4% in the input current waveform. However, it is noteworthy that method 2, referred to as the memory method, exhibited a sluggish and less robust transient response in comparison to the swift and resilient responses observed with method 1 and method 3. Additionally, the third proposed method, which involves a single current sensor positioned across the input inductor, emerged as the optimal and cost-effective sensing solution. This method achieved the same desirable attributes of fast and robust control while utilizing only a single current sensor, a notable advantage over method 1, which employs two current sensors. Full article

This paper reports the results obtained for a distributed-feedback quantum cascade laser (DFB-QCL) exposed to different fluences of proton particles: 10¹⁴, 10¹⁵ and 10¹⁶ p/cm². Dedicated laboratory setups were developed to assess the irradiation-induced changes in this device. Multiple parameters defining the QCL performances were investigated prior to and following each irradiation step: (i) voltage-driving current; (ii) emitted optical power-driving current; (iii) central emitting wavelength-driving current; (iv) emitted spectrum-driving current; (v) transversal mode structure-driving current, maintaining the system operating temperature at 20 °C. The QCL system presented, before irradiation, two emission peaks: a central emission peak and a side peak. After proton irradiation, the QCL presented a spectral shift, and the ratio between the two peaks also changed. Even though, after irradiation, the tunning spectral range was reduced, at the end of the tests, the system was still functional. Full article

In this paper, a new control scheme for buck converters was proposed. The buck converter utilizes the dual control loop to improve transient response and has the constant switching frequency. The control scheme is mainly as follows: (a) The switch-ON time is regulated by the constant frequency mechanism. (b) The switch-OFF time is regulated by the output voltage. The spec/features of the proposed converter are listed as: (1) The buck converter has an output of 1.0–2.5 V for the input of 3.0–3.6 V. The load current ranges from 100 mA to 500 mA. (2) The actual current sensor is not required. (3) The simulation results show that the recovery time is less than 1.6 μs during load changes. (4) The variation in switching frequency is smaller than 1.05% over the output range of 1.0–2.5 V. (5) This circuit can be fabricated in future by UMC 0.18 μm 1P6M CMOS processes. This paper depicts the control scheme, theoretical analysis, and implementation. Full article

This paper investigates the deadbeat current controllers for isolated bidirectional dual-active-bridge dc-dc converter (IBDC), including the peak current mode (PCM) and middle current mode (MCM). The controller uses an enhanced single phase shift (ESPS) modulation method by exploiting pulse width as an extra control variable in addition to phase shift ratio. The control variables for PCM controllers are derived in detail and the two different current controllers are compared. A double-closed-loop control method is then employed, which could directly control the high-frequency inductor current and eliminate the transient DC current bias of the transformer. Furthermore, load feedforward was introduced to further enhance the dynamic of the converter. With the proposed control method, the settling time could be reduced within several PWM cycles during load disturbance without transient DC current bias. A 5 kW IBDC converter prototype was built and the settling time of 6 PWM cycles during load change with voltage regulation mode was achieved, which verifies the superior dynamic performance of the control method. Full article

This paper aims to design an IPT for wireless charging of an e-bike and to control the charge of the e-bike from the primary-side. Optimum IPT design has been made according to the 36 V battery bank requirements. The no-load condition test has been performed before charging started in the IPT system connected to the AC grid. The primary-side DC-link voltage of 4–5 V required for this test is provided by the designed forward converter. The charge control has been also made from the forward converter on the primary-side. For this, the forward converter’s operation in peak current mode (PCM) has been used. Finally, a prototype has been implemented that works at a maximum DC/DC efficiency of 87.52% in full alignment and 83.63% in 3 cm misalignment. The proposed control algorithm has been tested in this prototype at different load stages. Full article

This paper proposes a novel control scheme for the buck converter without an inductor current sensor. The architecture of the proposed buck converter is simple and suitable for integration and mass production. It employs an output-voltage-measurement method to determine the switch ON time; therefore, the current sensor is not required. The design specification targets the application with a standard battery power source to generate the low voltages for low-power MCU or ASIC. The load current range aims for several hundred milliamps. The proposed control scheme is analyzed and simulated by SIMPLIS. The control scheme, theoretical analysis, circuit realization, contributions, advantages, and simulation results are presented in this paper. Furthermore, the circuit can be fabricated by a 0.35 μm CMOS process. Full article

This paper presents a novel buck converter with dual-loop control technology, which does not need to detect the inductor current directly. The structure of the control loops is easy to implement, one loop controls the output voltage, and the other controls the switching frequency. With the dual loops control mechanism, the output voltage and switching frequency can be accurately controlled only by measuring the output and input voltage, without sensing the inductor current. The buck converter can generate an output voltage of 1.0–2.5 V when the input voltage and load current are 3.0–3.6 V and 100–500 mA, respectively. The design was verified by SIMPLIS. The simulation results show that the switching frequency variation is less than 1% at the output voltage of 1.0–2.5 V. The recovery time is less than 1.5 μs during the load change. The circuit can be fabricated by using the TSMC 0.35μm 2P4M CMOS processes. The control scheme, theoretical analysis and circuit implementation are presented in this paper. Full article

This paper presents a buck converter with a novel constant frequency controlled technique, which employs the proposed frequency detector and adaptive on-time control (AOT) logic to lock the switching frequency. The control scheme, design concept, and circuit realization are presented. In contrast to a complex phase lock loop (PLL), the proposed scheme is easy to implement. With this novel technique, a buck converter is designed to produce an output voltage of 1.0–2.5 V at the input voltage of 3.0–3.6 V and the maximum load current of 500 mA. The proposed scheme was verified using SIMPLIS and MathCAD. The simulation results show that the switching frequency variation is less than 1% at an output voltage of 1.0–2.5 V. Furthermore, the recovery time is less than 2 μs for a step-up and step-down load transient. The circuit will be fabricated using UMC 0.18 μm 1P6M CMOS processes. The control scheme, design concept and circuit realization are presented in this paper. Full article

Thee peak-current-mode (PCM) control strategy is widely adopted in pulse width-modulated (PWM) DC-DC converters. However, the converters always involve a sub-harmonic oscillating state or chaotic state if the active duty ratio is beyond a certain range. Hence, an extra slope signal in the inductor-current loop is used to stabilize the operation of the converter. This paper presents a new technique for enlarging the stable range of PCM-controlled DC-DC converters, in which the concept of utilizing unstable period-1 orbit (UPO-1) of DC-DC converters is proposed and an implementation scenario based on the parameter-perturbation method is presented. With the proposed technique, perturbations are introduced to the reference current of the control loop, and the converters operating in a chaotic state can be tracked, and thus be stabilized to the target UPO-1. Therefore, the stable operating range of the converters is extended. Based on an example of a PCM-controlled boost converter, simulations are presented as a guide to a detailed implementation process of the proposed technique, and comparisons between the proposed technique and techniques in terms of ramp compensation are provided to show the differentiation in the performance of the converter. Experimental results in the work confirm the effectiveness of the proposed technique. Full article

Peak current-mode (PCM) control has been a very popular control method in power electronic converters. The small-signal modeling of the dynamics associated with PCM control has turned out to be extremely challenging. Most of the modeling attempts have been dedicated to the converters operating in continuous conduction mode (CCM) and just a few to the converters operating in discontinuous operation mode (DCM). The DCM modeling method published in 2001 was proven recently to be very accurate when applied to a buck converter. This paper provides the small-signal models for a boost converter and analyses for the first time its real dynamic behavior in DCM. The objectives of this paper are as follows: (i) to provide the full-order dynamic models for the DCM-operated PCM-controlled boost converter; (ii) to analyze the accuracy of the full and reduced-order dynamic models; and iii) to verify the validity of the high-frequency extension applied in the DCM-operated PCM-controlled buck converter in the case of the boost converter. It is also shown that the DCM-operated boost converter can operate only in even harmonic modes, similar to all the CCM-operated PCM-controlled converters. In the case of the DCM-operated PCM-controlled buck converter, its operation in the odd harmonic modes is the consequence of an unstable pole in its open-loop power-stage dynamics. Full article

Peak-current-mode (PCM) control was proposed in 1978. The observed peculiar behavior caused by the application of PCM-control in the behavior of a switched-mode converter, which operates in continuous conduction mode (CCM), has led to a multitude of attempts to capture the dynamics associated to it. Only a few similar models have been published for a PCM-controlled converter, which operates in discontinuous conduction mode (DCM). PCM modeling is actually an extension of the modeling of direct-duty-ratio (DDR) or voltage-mode (VM) control, where the perturbed duty ratio is replaced by proper duty-ratio constraints. The modeling technique, which produces accurate PCM models in DCM, is developed in early 2000s. The given small-signal models are, however, load-resistor affected, which hides the real dynamic behavior of the associated converter. The objectives of this paper are as follows: (i) proving the accuracy of the modeling method published in 2001, (ii) performing a comprehensive dynamic analysis in order to reveal the real dynamics of the buck converter under PCM control in DCM, (iii) providing a method to improve the high-frequency accuracy of the small-signal models, and (iv) developing control-engineering-type block diagrams to facilitate the development of generalized transfer functions, which are applicable for PCM-controlled DCM-operated buck, boost, and buck-boost converters. Full article